Chapter 16: In-Hospital Management of Diabetes

Canadian Diabetes Association 2013 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada

Introduction

Diabetes has been reported to be the fourth most common comorbid condition listed on all hospital discharges. In-hospital hyperglycemia is common in hospitalized patients and increases length of stay

Acute illness results in a number of physiological changes (e.g. increases in circulating concentrations of stress hormones) or therapeutic choices (e.g. glucocorticoid use) that can exacerbate hyperglycemia. Hyperglycemia may lead to decreased immune function and increased oxidative stress. This leads to a continuous cycle of worsening illness and poor glucose control.

Diagnosis of Diabetes and Hyperglycemia in the Hospital Setting

A history of diabetes should be elicited in all patients admitted to hospital and clearly identified on the medical record.

In view of the high prevalence of inpatient hyperglycemia with associated poor outcomes, an admission BG measurement should be considered for all patients even in the absence of a prior diagnosis of diabetes.

In-hospital hyperglycemia is defined as any glucose value >7.8 mmol/L.

A glycated hemoglobin (A1C) level should be drawn in all patients with known diabetes or with hyperglycemia if this has not been performed within 2 to 3 months of the admission.

Glycemic Control in the Noncritically Ill Patient

For the majority of noncritically ill patients treated with insulin, preprandial BG targets should be 5.0 to 8.0 mmol/L in conjunction with random BG values <10.0 mmol/L, as long as these targets can be safely achieved [Grade D, Consensus].

Lower targets may be considered in clinically stable patients with a prior history of successful tight glycemic control in the outpatient setting, while higher targets may be acceptable in terminally ill patients or in those with severe comorbidities.

If BG values are ≤3.9 mmol/L, the glucose-lowering therapy should be modified, unless the event is easily explained by other factors (e.g. a missed meal).

Glycemic Control in the Critically Ill Patient

Acute hyperglycemia in the intensive care setting is not unusual and results from a number of factors, including stress-induced counter-regulatory hormone secretion and the effects of medications.

Appropriate glycemic targets for patients with pre-existing diabetes who are critically ill (ICU setting) have not been firmly established.

Intensive insulin therapy has been associated with an increased risk of hypoglycemia in the ICU setting. Insulin infusion protocols with proven efficacy and safety are recommended to minimize the risk of hypoglycemia.

For most medical/surgical critically ill patients with hyperglycemia, a continuous IV insulin infusion should be used to maintain glucose levels between 8 and 10 mmol/L [Grade D, Consensus].

Perioperative glycemic control

Observational studies in humans have shown that hyperglycemia increases the risk of postoperative infections and renal allograft rejection, and is associated with increased resource utilization.

Intraoperative hyperglycemia during cardiopulmonary bypass has been associated with increased morbidity and mortality rates in individuals with and without diabetes.

Minor and moderate surgery

Perioperative glycemic levels should be maintained between 5.0 and 10.0 mmol/L for most other surgical situations, with an appropriate protocol and trained staff to ensure the safe and effective implementation of therapy and to minimize the likelihood of hypoglycemia [Grade D, Consensus].

However, the benefits of improved perioperative glycemic control must be weighed against the risk of perioperative hypoglycemia. Anesthetic agents and postoperative analgesia may alter the patient's level of consciousness and awareness of hypoglycemia.

Role of Subcutaneous Insulin

In general, insulin is the preferred treatment for hyperglycemia in hospitalized patients with diabetes.

Patients with type 1 diabetes must be maintained on insulin therapy at all times to prevent diabetic ketoacidosis (DKA).

For hospitalized patients with diabetes treated with insulin, a proactive approach that includes basal, bolus and correction (supplemental) insulin, along with pattern management, should be used to reduce adverse events and improve glycemic control, instead of the reactive sliding-scale insulin approach that uses only short- or rapid-acting insulin [Grade B, Level 2].

Scheduled subcutaneous (SC) insulin administration is the preferred method for achieving and maintaining glucose control in noncritically ill patients with diabetes or stress hyperglycemia who are eating.

Bolus insulin can be withheld or reduced in patients who are not eating regularly; basal insulin should not be withheld.

Sliding-scale insulin (SSI) (defined as the administration of a pre-established amount of short-acting insulin in response to hyperglycemia) as the sole regimen for the management of hyperglycemia in the hospital setting is ineffective in the majority of patients and, therefore, is not recommended.

Role of Oral Antihyperglycemic Drugs

Provided that their medical conditions, dietary intake and glycemic control are acceptable, people with diabetes should be maintained on their pre-hospitalization oral antihyperglycemic agents or insulin regimens [Grade D, Consensus].

There are often short- and/or long-term contraindications to the use of oral antihyperglycemic drugs (OADs) in the hospital setting, such as irregular eating, acute or chronic renal failure, and exposure to intravenous (IV) contrast dye.

However, if contraindications develop or if glycemic control is inadequate, these drugs should be discontinued and the patient should be started on a basal-bolus-supplemental insulin regimen.

Role of Medical Nutrition Therapy

Medical nutrition therapy is an essential component of inpatient glycemic management programs and should include nutritional assessment and individualized meal planning.

A consistent carbohydrate meal planning system may facilitate glycemic control in hospitalized patients and facilitate matching the prandial insulin dose to the amount of carbohydrate consumed.

Special Clinical Situations

Patients receiving enteral or parenteral feedings

In patients receiving parenteral nutrition (PN), insulin can be administered with the nutrition. Since nutrition is being provided continuously in patients receiving continuous enteral feeds, the TDD of insulin can be administered as long-acting, nonpeaking basal insulin alone (once daily glargine or twice daily detemir).

An IV infusion of regular insulin is often used initially to estimate the TDD of insulin required.

Approximately 80% of the TDD of insulin needed to maintain BG levels within the target range on IV insulin is added to the PN bags as regular insulin.

SC correction (supplemental) insulin is often used in addition to the insulin mixed with PN for unusual hyperglycemia.

To prevent ketoacidosis, patients with type 1 diabetes must be given subcutaneous insulin if the total parenteral nutrition (TPN) is interrupted. A separate IV insulin infusion may be used as an alternative.

Patients receiving bolus enteral feeds are typically treated like patients who are eating meals. Approximately 50% of the TDD is provided as basal insulin and 50% as bolus insulin, which is administered in divided doses to match feed times.

Short-acting regular insulin is usually selected over rapid-acting insulin in this group of patients because of the longer duration of action. Supplemental insulin should be administered as needed with the bolus insulin.

In the event that tube feeds are interrupted, IV dextrose may be required to prevent hypoglycemia.

Patients receiving corticosteroid therapy

Hyperglycemia is a common complication of corticosteroid therapy, with prevalence between 20% and 50% among patients without a previous history of diabetes.

Glycemic monitoring for at least 48 hours is recommended for patients with or without a history of diabetes.

For management, insulin is generally preferred, with an emphasis on adjusting bolus insulin doses as well as proactive insulin dose adjustment during corticosteroid dose tapering.

Patients using insulin pump therapy

Patients on insulin pump therapy do not necessarily need to discontinue this form of therapy while hospitalized, but must be assessed for their physical and mental competency to use their respective device.

If the patient cannot competently demonstrate and/or describe how to adjust their basal rate, administer a bolus dose, insert an infusion set, etc., insulin pump therapy should be discontinued and the patient placed on a SC insulin regimen or an IV insulin infusion.

Role of IV Insulin

IV insulin may be appropriate for patients who are critically ill, patients who are not eating or those who require prompt improvement in their glycemic control.

IV insulin protocols should take into account the patient's current and previous BG levels (and, therefore, the rate of change in BG), and the patient's usual insulin dose.

BG determinations should be performed every 1 to 2 hours until BG stability has been demonstrated.

With the exception of the treatment of hyperglycemic emergencies (e.g. DKA, hyperosmolar hyperglycemic state (HHS)), patients receiving IV insulin should receive some form of glucose (e.g. IV glucose or through TPN or enteral feeding).

Transition from IV insulin to SC insulin therapy

All patients with type 1 and type 2 diabetes should be transitioned to scheduled SC insulin therapy from IV insulin.

Short- or rapid-acting insulin should be administered 1 to 2 hours before discontinuation of the IV insulin to maintain effective blood levels of insulin. If intermediate- or long-acting insulin is used, it should be given 2 to 3 hours prior to IV insulin discontinuation.

Patients without a history of diabetes, who have hyperglycemia requiring more than 2 units of IV insulin per hour, should be transitioned to scheduled SC insulin therapy.

Organization of Care

Health care professional education, insulin protocols and order sets may be used to improve adherence to optimal insulin use and glycemic control [Grade C, Level 3].

The timely consultation of glycemic management teams has also been found to improve the quality of care provided, reduce the length of hospital stays and lower costs.

Competent adult patients who successfully self-manage their diabetes at home, have a stable level of consciousness and have the physical skills needed to self-administer insulin and perform self-monitoring of blood glucose (SMBG) may be provided with a physician order to continue self-management.

Transition from hospital to home

Patients and their family or caregivers should receive written and oral instructions regarding their diabetes management at the time of hospital discharge, which include:

Recommendations for timing and frequency of home glucose monitoring;

Identification and management of hypoglycemia;

A reconciled medication list, including insulin and other glucose-lowering medication;

Measures to assess, monitor and improve glycemic control within the inpatient setting should be implemented, as well as diabetes-specific discharge planning [Grade D, Consensus].

The frequency and timing of bedside BG monitoring should be individualized; however, monitoring is typically performed before meals and at bedtime in patients who are eating, every 4 to 6 hours in patients who are NPO (nothing by mouth) or receiving continuous enteral feeding, and every 1 to 2 hours for patients on continuous IV insulin.

Safety

Hypoglycemia

Hypoglycemia remains a major barrier to achieving optimal glycemic control in hospitalized patients.

In hospitalized patients, hypoglycemia should be avoided.

Protocols for hypoglycemia avoidance, recognition and management should be implemented with nurse-initiated treatment, including glucagon for severe hypoglycemia when IV access is not readily available [Grade D, Consensus].

Patients at risk of hypoglycemia should have ready access to an appropriate source of glucose (oral or IV) at all times, particularly when NPO or during diagnostic procedures [Grade D, Consensus].

Health care workers should be educated about factors that increase the risk of hypoglycemia, such as sudden reduction in oral intake, discontinuation of PN or enteral nutrition, unexpected transfer from the nursing unit after rapid-acting insulin administration or a reduction in corticosteroid dose.

Insulin administration errors

A systems approach that includes preprinted, approved, unambiguous standard orders for insulin administration and/or a computerized order entry system may help reduce errors.